1. Field of the Invention
The present invention relates to systems and methods for remodeling soft tissue of a patient. More specifically, the present invention relates to drawing tissue portions toward one another to, for example, reduce or close body cavities or lumens, such as heart chambers, heart valves and other generally hollow anatomical structures.
2. Description of the Related Art
Several surgical techniques have been developed to close defects in tissue, reduce or close tubular structures, remodel cavities and repair bodily valves. However, the existing techniques require surgery or, even if non-invasive, suffer from significant drawbacks. For example, existing techniques may be generally difficult to perform, leave large residual foreign materials in the body, or not very effective in achieving the desired results.
For example, with respect to vascular or heart tissue remodeling, minimally invasive methods are fairly complex and often leave devices, such as stents, umbrellas, disks, plugs or rods, within a blood pathway of the body, which could promote thrombus formation. With respect to mitral or aortic regurgitation, minimally invasive methods typically insert a rod or similar apparatus within the coronary sinus. However, such a method could lead to erosion of the coronary sinus or other problems to the patient. Alternative devices and methods that attach the valve leaflets together to reduce regurgitation could lead to tears in the leaflets, which could require further surgery.
To properly and consistently repair the mitral valve, the following variables are relevant: the annular diameter, the leaflet length, the chordal length and the attachment point of the chords. Fortunately, the leaflet length is relatively constant. The annulus diameter can be fixed by the annuloplasty ring. The chords can be replaced by polytetrofluorethylene suture to fix their length. The missing variable is the attachment of the chords to the left ventricle. To date, this remains a troublesome variable to the valve repair.
Ischemic mitral regurgitation occurs when there is ventricular dysfunction which causes the posterolateral attachments of the mitral valve to be drawn away from the annulus in systole. This pulls the two leaflet edges apart at their point of coaptation and produces an asymmetrical regurgitate jet or, in other words, blood flow in the wrong direction through the valve. In an ideal situation, the leaflets, the chords and the attachment points are all anatomically normal. Sometimes there is a relative discrepancy between the distances the anterior leaflet is drawn inward relative to the posterior leaflet so they are not just separated from edge-to-edge but also there is a step deformity of the junction point. The patient may also have some underlying mild degree of degenerative deformity which may initially cause a mild, but well-tolerated degree of mitral regurgitation. However, the regurgitation often becomes severe after left ventricular ischemia occurs.
Some repair techniques apply tight annuloplasty rings which serve to buckle the leaflets and draw them together to, for example, correct ischemic disease. This often leaves a degree of mitral regurgitation and mitral stenosis results. However, long term results seem to degenerate after a couple of years due to the continuing of the dilation in the ventricle it self, which changes the attachment point position in regard of the annulus and by pulling on the chords, the leaflet edges will no longer coapt, thereby producing regurgitation. Accordingly, a need exists for improved minimally invasive tissue remodeling devices and methods in general, and particularly for the purpose of adjusting the location of the attachment of the chords to the left ventricle relative to the valve annulus.